/***
 * ASM: a very small and fast Java bytecode manipulation framework
 * Copyright (c) 2000-2013 INRIA, France Telecom
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.springframework.asm;

/**
 * The path to a type argument, wildcard bound, array element type, or static
 * inner type within an enclosing type.
 *
 * @author Eric Bruneton
 */
public class TypePath {

	/**
	 * A type path step that steps into the element type of an array type. See
	 * {@link #getStep getStep}.
	 */
	public static final int ARRAY_ELEMENT = 0;

	/**
	 * A type path step that steps into the nested type of a class type. See
	 * {@link #getStep getStep}.
	 */
	public static final int INNER_TYPE = 1;

	/**
	 * A type path step that steps into the bound of a wildcard type. See
	 * {@link #getStep getStep}.
	 */
	public static final int WILDCARD_BOUND = 2;

	/**
	 * A type path step that steps into a type argument of a generic type. See
	 * {@link #getStep getStep}.
	 */
	public static final int TYPE_ARGUMENT = 3;

	/**
	 * The byte array where the path is stored, in Java class file format.
	 */
	byte[] b;

	/**
	 * The offset of the first byte of the type path in 'b'.
	 */
	int offset;

	/**
	 * Creates a new type path.
	 *
	 * @param b      the byte array containing the type path in Java class file
	 *               format.
	 * @param offset the offset of the first byte of the type path in 'b'.
	 */
	TypePath(byte[] b, int offset) {
		this.b = b;
		this.offset = offset;
	}

	/**
	 * Returns the length of this path.
	 *
	 * @return the length of this path.
	 */
	public int getLength() {
		return b[offset];
	}

	/**
	 * Returns the value of the given step of this path.
	 *
	 * @param index an index between 0 and {@link #getLength()}, exclusive.
	 * @return {@link #ARRAY_ELEMENT ARRAY_ELEMENT}, {@link #INNER_TYPE
	 * INNER_TYPE}, {@link #WILDCARD_BOUND WILDCARD_BOUND}, or
	 * {@link #TYPE_ARGUMENT TYPE_ARGUMENT}.
	 */
	public int getStep(int index) {
		return b[offset + 2 * index + 1];
	}

	/**
	 * Returns the index of the type argument that the given step is stepping
	 * into. This method should only be used for steps whose value is
	 * {@link #TYPE_ARGUMENT TYPE_ARGUMENT}.
	 *
	 * @param index an index between 0 and {@link #getLength()}, exclusive.
	 * @return the index of the type argument that the given step is stepping
	 * into.
	 */
	public int getStepArgument(int index) {
		return b[offset + 2 * index + 2];
	}

	/**
	 * Converts a type path in string form, in the format used by
	 * {@link #toString()}, into a TypePath object.
	 *
	 * @param typePath a type path in string form, in the format used by
	 *                 {@link #toString()}. May be null or empty.
	 * @return the corresponding TypePath object, or null if the path is empty.
	 */
	public static TypePath fromString(final String typePath) {
		if (typePath == null || typePath.length() == 0) {
			return null;
		}
		int n = typePath.length();
		ByteVector out = new ByteVector(n);
		out.putByte(0);
		for (int i = 0; i < n; ) {
			char c = typePath.charAt(i++);
			if (c == '[') {
				out.put11(ARRAY_ELEMENT, 0);
			} else if (c == '.') {
				out.put11(INNER_TYPE, 0);
			} else if (c == '*') {
				out.put11(WILDCARD_BOUND, 0);
			} else if (c >= '0' && c <= '9') {
				int typeArg = c - '0';
				while (i < n && (c = typePath.charAt(i)) >= '0' && c <= '9') {
					typeArg = typeArg * 10 + c - '0';
					i += 1;
				}
				if (i < n && typePath.charAt(i) == ';') {
					i += 1;
				}
				out.put11(TYPE_ARGUMENT, typeArg);
			}
		}
		out.data[0] = (byte) (out.length / 2);
		return new TypePath(out.data, 0);
	}

	/**
	 * Returns a string representation of this type path. {@link #ARRAY_ELEMENT
	 * ARRAY_ELEMENT} steps are represented with '[', {@link #INNER_TYPE
	 * INNER_TYPE} steps with '.', {@link #WILDCARD_BOUND WILDCARD_BOUND} steps
	 * with '*' and {@link #TYPE_ARGUMENT TYPE_ARGUMENT} steps with their type
	 * argument index in decimal form followed by ';'.
	 */
	@Override
	public String toString() {
		int length = getLength();
		StringBuilder result = new StringBuilder(length * 2);
		for (int i = 0; i < length; ++i) {
			switch (getStep(i)) {
				case ARRAY_ELEMENT:
					result.append('[');
					break;
				case INNER_TYPE:
					result.append('.');
					break;
				case WILDCARD_BOUND:
					result.append('*');
					break;
				case TYPE_ARGUMENT:
					result.append(getStepArgument(i)).append(';');
					break;
				default:
					result.append('_');
			}
		}
		return result.toString();
	}
}
